The invention relates to electromagnetic shielding, and more specifically, to electromagnetic shielding of fiber-optic modules.
As the need for greater data bandwidth over networks has exploded over the past few years, there has been a move towards using optical fibers as a transmission medium. Today, optical fiber made of dielectric materials are routinely used in communication channels from large public transmission media to Local Area Networks transmitting information from one node to another. The main difference between a fiber-optic communication system and other types of communication systems is that signals are transmitted as light or photons over optical fibers. Optical fiber or fiber-optic cables enable high speed communication of signals by guiding light or photons therein. At each end of a fiber-optic cable a transducer may be found that converts a light, photon or optical signal into an electrical signal; an electrical signal into a light, photon or optical signal; or a pair of transducers may do both. At a transmission end, an electrical-to-optical converter (EO) converts electrical signals into light or optical signals. At a receiving end, an optical-to-electrical converter (OE) converts a light, photon or optical signal into an electrical signal. In nodes of a communication system, it may be desirable to both transmit and receive light or optical signals at a node. In which case an optical-to-electrical converter (OE, i.e. receiver) and an electrical-to-optical converter (EO, i.e. transmitter) may be included to receive and transmit optical or light signals respectively. Therefore, the optical-to-electrical converter (OE, i.e. receiver) and the electrical-to-optical converter (EO, i.e. transmitter) are oftentimes physically located together as a single module referred to as an electro-optic, opto-electronic or fiber-optic transceiver. Fiber-optic transceivers, including fiber-optic transmitters and fiber-optic receivers, can also be referred to as fiber-optic modules.
Because of the high frequency needed in some of the electronics and the electro-optic components, such as the optical-to-electrical converter (OE, i.e. receiver) and electrical-to-optical converter (EO, i.e. transmitter), electromagnetic radiation can be generated which can interfere with other communication systems. This electromagnetic radiation is oftentimes referred to as electromagnetic interference (EMI). Electromagnetic radiation radiating externally out from a fiber-optic module or a system that incorporates the fiber-optic module is of great concern. To reduce electromagnetic radiation from radiating out of fiber-optic modules and systems with fiber optic modules as EMI, external electromagnetic shielding of internal electronic and opto-electronic components is often utilized. The external electromagnetic shielding can additionally reduce effects of external electromagnetic radiation on the internal components of a fiber-optic module and the system.